 
 (defn multirember [a lat]
   (cond
-    (null? lat) '()
+    (null? lat) []
     (= (first lat) a) (multirember a (rest lat))
     :else (cons (first lat)
                 (multirember a (rest lat)))))
 
 (defn multiinsertR [n o lat]
   (cond
-    (null? lat) '()
+    (null? lat) []
     (= (first lat) o) (cons o (cons n
                                     (multiinsertR n o (rest lat))))
     :else (cons (first lat)


(defn no-nums [lat]
    (cond
        (null? lat) '()
        (number? (first lat)) (no-nums (rest lat))
        :else (cons (first lat)
                    (no-nums (rest lat)))))

(defn all-nums [lat]
    (cond
        (null? lat) '()
        (not (number? (first lat))) (all-nums (rest lat))
        :else (cons (first lat)
                    (all-nums (rest lat)))))


(defn multisubst [n o lat]
  (cond
    (null? lat) []
    (= (first lat) o) (cons n
                            (multisubst n o (rest lat)))
    :else (cons (first lat)
